Fill empty blocks in your outlook calendar for the next week

FillCalendarForPeriod.ps1

param (
    [int] $DaysForward = 7,
    # What hour of the day do you start?
    [int] $DayStart = 8,
    # How many hours after that are work hours?
    [int] $DayLength = 10
)

function Get-OutlookCalendar {
    param (
        $StartDate,
        $EndDate
    )
    Add-type -assembly "Microsoft.Office.Interop.Outlook" | out-null
    $olFolders = "Microsoft.Office.Interop.Outlook.OlDefaultFolders" -as [type] 
    $outlook = new-object -comobject outlook.application
    $namespace = $outlook.GetNameSpace("MAPI")
    $folder = $namespace.getDefaultFolder($olFolders::olFolderCalendar)
    $filter = "[START] >= '$StartDate' and [END]<= '$EndDate'"

    $folderItems = $folder.items
    $folderItems.IncludeRecurrences = $true
    $folderItems.Sort("[Start]")
    $folderItems = $folderItems.Restrict($filter)

    $folderItems #| Select-Object -Property Subject, Start, Duration, Location, ResponseStatus, BusyStatus
} 

function BlockOffDay($Start, $End) {
    "$Start -> $End"
    $entries = Get-OutlookCalendar -StartDate $Start.ToString("M/d/yyyy") -EndDate $End.ToString("M/d/yyyy")

    # Clean out the existing work items to allow the calendar to be 'cleaner'
    foreach ($entry in $entries) {
        if($entry.Subject -eq "Work") {
            "Removing $($entry.Subject) - $($entry.Start) - $($entry.End)"
            $entry.Delete()
        }
    }

    # repopulate the entries.
    $entries = Get-OutlookCalendar -StartDate $Start.ToString("M/d/yyyy") -EndDate $End.ToString("M/d/yyyy")
    $freeTime = @()

    for ($i = 0; $i -lt ($DayLength * 60); $i++) {

        if (($i % 60) -eq 0) {
            $currentHour = $DayStart + $i / 60
        }

        $currentSlot = Get-Date -Hour $currentHour -Minute ($i % 60) -Second 00 -Year $Start.Year -Month $Start.Month -Day $Start.Day
        $booked = $false
    
        foreach ($entry in $entries) {
            $entryEnd = $entry.Start.AddMinutes($entry.Duration)
            $booked = $currentSlot -ge $entry.Start -and $currentSlot -le $entryEnd

            if ($booked -and ($entry.ResponseStatus -eq 4 -or $entry.ResponseStatus -eq 5 -or $entry.ResponseStatus -eq 2)) {
                #"Not Accepted, ignore $($entry.Subject)"
            }
            elseif ($booked) {
                #"Checking $($entry.Subject)"
                if ($booked) {break}
            }
        }

        if ($booked) {
            #"$currentSlot - Booked"
        }
        else {
            #"$currentSlot - Free"
            $freeTime += $currentSlot
        }
    }

    [Math]::Round(($freeTime[150] - $freeTime[149]).TotalMinutes)
    $bookingBlocks = @()
    $slotStart = $freeTime[0]
    for ($i = 1; $i -lt $freeTime.Count; $i++) {
        #$freeTime[$i]
        if ([Math]::Round(($freeTime[$i] - $freeTime[$i - 1]).TotalMinutes) -gt 1) {
            $bookingBlocks += @{Start = $slotStart; End = $freeTime[$i - 1]}
            "BLOCK: $slotStart -> $($freeTime[$i-1])"
            $slotStart = $freeTime[$i]
        }
        else {
            #"BLOCK: $slotStart -- $($freeTime[$i]) -- $(($freeTime[$i] - $freeTime[$i-1]).TotalMinutes) -- $i"
        }
    }

    $bookingBlocks += @{Start = $slotStart; End = $freeTime[-1]}
    "BLOCK: $slotStart -> $($freeTime[-1])"

    $outlook = new-object -com Outlook.Application
    $namespace = $outlook.GetNameSpace("MAPI")
    $olFolders = "Microsoft.Office.Interop.Outlook.OlDefaultFolders" -as [type] 
    $calendar = $namespace.getDefaultFolder($olFolders::olFolderCalendar)
    foreach ($block in $bookingBlocks) {

        if ($block.Start -ne $block.End) {
            $appt = $calendar.Items.Add(1) # == olAppointmentItem 
            $appt.Start = $block.Start
            $appt.End = $block.End
            $appt.Subject = "Work"
            $appt.BusyStatus = 2
            $appt.Location = ""
            $appt.Body = ""
            $appt.ReminderSet = $false
            $appt.Categories = "WORK"
            $appt.Save()
        }
            
    }

}

for ($i = 0; $i -lt $DaysForward; $i++) {
    "$(([datetime]::Today).AddDays($i).DayOfWeek) to $(([datetime]::Today).AddDays($i + 1).DayOfWeek)"
    if(([datetime]::Today).AddDays($i + 1).DayOfWeek -eq [System.DayOfWeek]::Sunday -or ([datetime]::Today).AddDays($i + 1).DayOfWeek -eq [System.DayOfWeek]::Monday) {
        "Skipping $(([datetime]::Today).AddDays($i + 1).DayOfWeek)"
    } else {
        BlockOffDay -Start ([datetime]::Today).AddDays($i) -End ([datetime]::Today).AddDays($i+1)
    }
}